Necrotizing enterocolitis (NEC) is the most common serious gastrointestinal disorder of infancy, affecting one to five percent of intensive care unit admissions. In a nationwide epidemiological study, more than 25% of infants weighing less than 1500 grams had suspected or confirmed NEC during their stay in the intensive care unit. More than 50% of very low birth weight infants with stage III disease died as a result of NEC. This study has 2 specific aims: (1) to prospectively investigate the relationship between plasma cytokine levels of IL-6, TFN-alpha, and platelet activating factor (PAF) and development and progression of necrotizing enterocolitis; (2) to determine cytokine (TFN-a and PAF) mRNA levels in isolated intestinal segments removed at the time of surgery from infants with necrotizing enterocolitis or intestinal atresia.